Phylogeny and morphological traits evolution of Astragalus sects. Acanthophace and Aegacantha in Iran on the basis of nrDNA ITS and rpl32-trnLUAG sequences

In this study, phylogenetic relationships and evolutionary trends of morphological characters of Astragalus sects. Acanthophace and Aegacantha were studied using nrDNA ITS and rpl32-trnLUAG datasets while Astragalus stocksii was selected as the outgroup. The phylogenetic results indicated the non-monophyly of A. sect. Acanthophace in its current circumscription due to the distant exclusion of A. ovigerus from the core group, and incongruence between nuclear and plastid datasets on the basis of different position of latter species in the resulted phylogenetic trees. Astragalus sect. Aegacantha was also found to not being monophyletic due to the distant position of A. montis-parrowii from the other representatives of the section while accompanying with other spiny Astragalus species. The Optimization of 32 morphological characters on the Bayesian combined tree indicated that some characters were most useful for delimitation of taxa in sections Acanthophace and Aegacantha. The results obtained from the evolution of characters showed that standard blade constriction, legume shape and possessing unilocular pods were of diagnostic importance for the separation of A. ovigerus from other species. The traced characters were in accordance with the phylogenetic position of A. montis-parrowii, which was separated from other members of sect. Aegacantha, as the number of flowers in inflorescences, the presence of peduncle, hairy petal, pandurate standard and constriction of standard that is differentiatiated to claw, the presence of claw in standard and the length difference between keel and wing were different from those in other members of the sect. Aegacantha.